Field of the Invention
The invention relates in general to a touch panel, a touch display panel and a touch display device, and more particularly to a touch panel, a touch display panel and a touch display device whose electrode pattern has an arc.
Description of the Related Art
Referring to FIG. 1, a schematic diagram of forming a black matrix (BM) on a substrate of a touch panel is shown. In order to better describe the relationship between the substrate 10 and the black matrix 11, the substrate 10 does not completely overlap the black matrix 11 in FIG. 1.
During the manufacturing process of the touch sensor, the black matrix 11 with an opening is formed on the substrate 10. The opening of the black matrix 11 is formed at a display area 10b of the substrate 10, and the black matrix is formed on a mask area 10a of the substrate 10. As indicated in FIG. 1, the black matrix 11, used for masking the light source, includes an external edge Eext and an inner edge Ein, wherein the inner edge Ein represents the periphery of the display area 10b. 
Referring to FIG. 2, a schematic diagram of a transparent electrode layer is shown. The transparent electrode layer 13 includes plural electrode patterns (ITO sensor patterns) arranged in M rows and N columns. The electrode patterns at the same row and adjacent to each other jointly form horizontal electrodes 131. The electrode patterns at the same column and adjacent to each other jointly form vertical electrodes 132. The horizontal electrodes 131 and the vertical electrodes 132 are interlaced to form an array of electrode patterns.
The transparent electrode layer 13 is formed on the substrate 10 and the black matrix 11. The part of the electrode patterns adjacent to the external edge of the transparent electrode layer 13 is formed on the mask area of the substrate 10 and the black matrix 11. On the other hand, the part of electrode patterns at the center of the transparent electrode layer 13 is formed at the opening of the black matrix 11 (that is, at the display area of the substrate 10).
After formation of the black matrix 11, the manufacturing process of touch display panel further includes the manufacturing processes of a display layer, a conductive layer, an insulating layer and so forth. These subsequent manufacturing processes require the condition of high temperature (such as 300° C.). Since the black matrix 11 cannot resist high temperature, the high temperature in subsequent manufacturing processes will make the black matrix 11 carbonized. The carbonized black matrix 11 has lower resistance, and may even have slight conductivity.
Meanwhile, the sharper and tinier the electrode patterns (ITO Sensor pattern) are formed on the black matrix 11, the higher the density of electric charges and the intensity of electric fields will be. When the electric charges on the electrode patterns of the transparent electrode layer 13 accumulate to a certain degree and generate significant voltage difference between the transparent electrodes, the phenomenon of point discharge will occur to the electrode patterns. When the phenomenon of point discharge occurs, the black matrix 11 with slight conductivity will be hit by electrostatic discharge (ESD), which may cause light leakage inside the panel or make the transparent electrodes short-circuited.